Seeking the best "pay back" ? ?

[anisa]

Ok, so I have a dear friend whose going through a hard time. She's been married to this guy for 5 years, on and off marriage. They have 2 kids together. Everytime he decides to leave her, he forgets about his kids, makes a new facebook page with all his bad friends, his ex's and he knows she sees that all. I can't blame him but her for always being behind his A**. Shes always calling his mom to find out about him, she (his mom) always replies with the same thing "he doesn't mention you, only the kids"- shes constantly crying over him. She sends him msgs and blames herself when its him! She tries to call his mom so he can see the kids but he doesn't care. The day he left she didn't even know. I tell her to stop calling his mom, stop looking at his facebook and plan a trip to escape from this jerk! So she went ahead and even told his mom about the trip to see if she told him and wait for his reaction? What can I advise my friend without truly hurting her. What can she do to hurt him?